Half of patients with Alzheimer’s disease have mild symptoms of dementia, a group of researchers at the Boston University School of Medicine said Wednesday.

Using data from the Framingham Heart Study, the researchers found that 50.4 percent of the patients had mild symptoms, 30.3 percent had moderate symptoms and 19.3 percent had severe cases.

The Framingham Heart Study is a long-term cardiovascular cohort study of residents of the city of Framingham, Massachusetts. The study began in 1948 with 5,209 adult subjects and is now on its fourth generation of participants.

“Early intervention in (mild cognitive impairment) or the mild stage of (Alzheimer’s disease) dementia has been the primary focus for (Alzheimer’s disease) research and drug development in recent years,” said Rhoda Au, one of the study’s authors and a professor at Boston University.

According to the US Alzheimer’s Association, mild cognitive impairment causes a slight but noticeable and measurable decline in cognitive abilities, including memory and thinking skills. A person with mild cognitive impairment is at increased risk of developing Alzheimer’s or another form of dementia.

“Our results serve to inform the design of future research studies such as clinical and observational studies and provide optimal resource allocation for policy-making,” Au said.

As the study shows that half of those living with Alzheimer’s disease have mild symptoms, the researchers said it highlights the need for research and intervention to slow down the progress of the dementia.

“It is crucial to determine risk factors or develop therapies that could alter the disease trajectory to improve individuals’ quality of life and alleviate the socio-economic burden,” Au said.

The findings were published in the Journal of Alzheimer’s Disease in December.

By Kan Hyeong-woo (hwkan@heraldcorp.com)